The present invention relates to a new and improved apparatus and method for detecting the presence of ice on a surface of a member and, more specifically, to an apparatus for detecting the presence of ice on a surface of an aircraft wing.
It is a common practice to have a physical inspection of the wings of aircraft at a terminal to determine if ice has formed on the wing. Conducting a physical inspection for ice on aircraft wings at the terminal is time consuming and expensive. Therefore, it has previously been suggested that an ice detection system be provided in association with the wing of an aircraft. An ice detection system should be relatively low in cost and easily installed.
A system for detecting ice on a wing of an aircraft must provide a fault-free, false-alarm-free indication of the presence of ice. The reliability of the detection system must be sufficient to enable physical inspections to be eliminated. Therefore, a system which reliably detects the presence of ice on the wing of an aircraft would be desirable.
An apparatus for detecting the presence of ice on the wing of an aircraft is disclosed in U.S. Pat. No. 4,819,480. The apparatus disclosed in this patent utilizes a heat flux transducer to measure heat flow. When ice is present, the thermal impedance of the ice causes a smaller amount of heat to flow through the transducer. The reduced rate of heat flow through the transducer indicates the formation of ice on a portion of the aircraft.
Another ice detection system is disclosed in U.S. Pat. No. 3,305,851. The ice detection system disclosed in this patent uses a thermo-electric element to detect the formation of ice on a wing of an aircraft. The rate at which power is supplied to the thermo-electric element is varied as a function of the temperature of a cold surface on the thermo-electric element and a surface on the leading edge of a wing. Other ice detection systems are disclosed in U.S. Pat. Nos. 4,766,369 and 4,882,574.